Off-peak water heating system



De@ 16, 1941 c. M. osTERHELn OFF-PEAK WATER HEATING SYSTEM Filed Nov. 16, 1940 2 Sheets-Sheet l xNvENroR 0L ARK 0s rem/1D BY M i ATTORNE Y Dec. 16, 1941. c, M. osTERHELD 2,266,251

OFF-PEAK WATER HEATING SYSTEM INVENTOR CLARK GS75/waz? BY I ATTORNEY Patented Dec. 16, 1941 OFF-PEAK WATER HEATING SYSTEM Clark M. Osterheld, Stoughton, Wis., assigner to McGraw Electric Company, Elgin, Ill., a corporation of Delaware Application November 16, 1940, Serial No. 385,921

(Cl. 21S-39) 6 Claims.

My invention relates to electric water heating systems and particularly to off-peak water heating systems.

An object of my invention is to provide a relatively simple time and thermally controlled switching means effective to ensure a certain sequence of energization with respect to time and temperature of an electric heater on a hot water tank.

Other objects of my invention will either be apparent from a description of several forms of systems embodying my invention `or will be pointed out in the course of such description and set forth in the appended claims.

In the drawings,

Figure 1 is a schematic view of control means embodying my invention as applied to an ordinary domestic hot water tank,

Fig. 2 is a view of one control element shown in a certain operating position,

Fig. 3 is a view similar to Fig. 1 but showing a slightly modified form of timing means, and,

Fig. 4 is a view of one element of my system ln a certain operating position.

My off-peak water heating system is particularly adapted to provide relatively few, simple and inexpensive means for ensuring energization of the single heater of a hot water tank at the start of an off-peak period in case more than a predetermined fractional part of the water content of the tank is cold at the start of an off-peak period, to delay energization for a preset fixed delay time after the start of an off-peak period in case more than said predetermined fractional part of the water content is hot, to ensure energization after such delay irrespective of the condition, as to temperature, of a fractional part of the water content and continuation of the energization until the end of an off-peak period in case all of the water in the tank is not hot before the end of an off-peak period.

Referring first to Fig. 1 of the drawings, I have there illustrated a continuously operative timing means Il here shown generally as including a continuously operative synchronous motor I3 electrically connected to supply circuit conductors l5 and l1 which are to be considered as being energized continuously so that the motor I3 will also be continuously operative. A worm gear i9 on the motor shaft meshes with a worm wheel 2| which is mounted on a shaft 23. A cam disc 25 having a uniform outer radius over a given portion and a portion 21 of larger outer radius thereon is adapted to be adjustably simple worm gear with a single reduction only, I desire it to be understood that this is shown for illustrative purposes only and it is to be understood as including any desired or necessary means to cause one complete rotation of the shaft 23 and of the cam disc 25 in a twenty-four hour day.

I have illustrated the peripheral extent of the portion 21 as about one-third of the total periphery so that its time extent will be substantially eight hours. I desire it to be understood also that the position occupied by the cam disc 21 is that which it may be considered to occupy at 10:00 p. m., the start of an ofi-peak period, which would therefore end at substantially 6:00 a. m. While I have shown a specific setting of the cam disc 25 and a given peripheral extent of the portion 21, I do not desire to be limited thereto since I may vary not only the peripheral extent but also the time of start and of end of an off-peak period.

I provide a timer-actuated main heater-control switch 29 including a relatively rigid contact arm 3| and a resilient contact arm 33 normally yieldingly biased out of engagement with the arm 3| but adapted to be moved into engagement therewith when a lug 35, of electric-insulating material mounted on arm 33 is engaged by the portion 21 of disc 25. It is evident, therefore, that the contact arms 33 and 3l will be held in engagement with each other during substantially the entire duration of an ofi-peak period, the duration of which as Well as its time of starting and ending is adjustable.

I provide further an auxiliary timer-controlled heater-control switch 31. which includes a relatively rigid contact arm 39, a resilient contact arm 4I normally yieldingly biased out of engagement with arm 3! but moved into engagement therewith when a lug 43, of electric-insulating material, mounted on the arm 4l engages a portion 45, of larger outer radius, constituting a part of an auxiliary cam disc 41, this occurring after a preset delay period after the start of anoi-peak period. I have shown a given peripheral extent of the portion 45 but it is to be understood that while, in the position shown in Fig. l, portion 45 extends beyond 4the portion 21, it is only necessary that the portion 45 be co-extensive with the end portion (as to time) of cam portion 21 so that the auxiliary switch 31 may ce held closed until the end of an off-peak period. I have shown a set screw 49 by means of which auxiliary disc 41 may be adjustably mounted mounted on the shaft 23. While I have shown a against one face of cam disc 25. It will be noted I that lug 63 on arm ll-4 will not engage portion 65 adjustable vas has just been set forth above.

My improved water heating system is particularly adapted for use with a tank of the ordinary elongated cylindrical type used in homes and this tank may be provided with a cold water inlet pipe 53 and a hot water outlet pipe 55 connected therewith in the usual manner now well known in the art. I may surround the tank 5| by a mass 51 of heat-insulating material and I may further provide an outer casing 59 to protect the heat-insulating material.

I provide a single electric heating element 6| which is illustrated schematically only as I may use any kind of heating element now well known inthe art including that disclosed and claimed in my Patent No. 2,226,526` issued December 24, 1940. The heater 6| is to be understood as being of substantially annular shape and may be mounted in a tunnel member 53, all as set forth in my above mentioned patent.

I provide a main thermally actuable heater control switchr 85 responsive to tank water temperature and this switch includes a tubular member t1 connected in'a uid-tight manner with the wall of tank 5| to be positioned within the tank. The switch includes further an expansion rod 69, a relatively rigid contact arm 1| and a resilient contact arm 13 normally yieldingly biased into engagement with contact arms 1| but adapted to be moved out of engagement therewith by expansion of rod 59 when tubular member 61 is subject to hot Water. I desire it to be understood that the design, construction and location of thermal switch85 and of the heater 6| are such that thermal switch 65 will not cause disengagement of its contact arms until substantially all of the -water in the tank is hot.

I provide further an auxiliary thermal switch responsive to tank water temperature at an upper point in the tank and while I have shown this auxiliary heater control switch 15 as positioned just above about the middle of the tank, I do not desire to be limited thereto since it may be positioned at any point desired by the user or by the central station engineers as regards the height of the tank. y

The switch 15 includes a tubular member 11 secured in a huid-tight manner to the tank 5| to be positioned 'within the tank,- an expansion rod 19, a relatively rigid contact arm 8| and a vresilient contact arm 83 normally yieldingly biased into engagement with contact arm 8| and adapted to be disengaged therefrom when tubular member 11 is subject to hot water. It is, therefore, evident that the position of the auxiliary upper thermal switch 15 will determine the amount of hot water in the tank required to cause it to interrupt any circuit controlled by it. The amount of water hot or cold necessary to cause operation of this auxiliary thermal switch is therefore denoted generally by a predetermined fractional part ofthe water content of the tank.

The electric circuit connections between all of the switches, the heater and the supply circuit conductors are as follows: A conductor 85 connects supply circuit conductor |5 to contact arm 33 of main timer-controlled switch 23. A conductor 3l" connects contact arm 3| to contact arm t3. A conductor 83 connects contact arm'l with contact arm 3| of the auxiliary switch 31. Contact arm 39 of auxiliary switch 31 is connected by a conductor 9| to contact arm 3| and therefore also to conductor 81. Conductor 89 is connected by a conductor 93 to Contact arm 1|. Contact arm 'I3 is connected by a conductor 95 to one terminal of heater 6|, the other terminal of which is connected by a conductor 91 to the other supply circuit conductor |1. 1I

Let it be assumed, L-for illustrative purposes, that the amount of hot water in the tank at the start of an off-peak period is such that both the main and the auxiliary thermal switches are subject to cold water. This will mean that both thermal switches are in closed position at the time of closure of the main timer-controlled switch 29, at say 10:00 p. m., which is the position shown in Fig. 1 of the drawings for the continuously operative timing means Under the hereinbefore mentioned conditions considered to be existing at the time of start of an oil-peak period, an energizing circuit through the heater 6| will be closed as follows: From supply circuit conductor I5, through conductor` 85, through engaged contact arms 33 and 3|. through conductor 81, through engaged contact arms 83 and 8|, through conductor 93, through engaged contact arms '1| and 13, through conductor to the heater 8| and from there through conductor 91 to the other supply circuit conductor Il. This will therefore cause energization of the heater co-incident with the start of an off-peak period and it may here be pointed out that this circuit includes the main timercontrolled switch and the auxiliary and the main thermal heater control switches all connected in series circuit relation relatively to each other.

Let it now be assumed that at the time of start of an oir-peak period the amount of hot'water `in the tank was such as to surround the auxiliary thermal switch 15 with hot water with the attendant condition of this switch that it is in open position, with the contact arms disengaged from each other. The hereinbefore described energizing circuit through the heater 6| will therefore notA be established, the thermal switch 15 precluding the establishment ofl such a heater energizing circuit.

Under the last above named conditions, that is,

that the auxiliary thermal switch 15 isl responsive to hot water, there will be a delay of an adjustably preset length of time lafter the start of an off-peak period, the start of the energization ofv the heater 6| being eiected, more particularly, by the auxiliary timer-controlled switch 31 which is moved into closed position by the auxiliary cam disc 41 at an adjustably later time than that at which the main timer-controlled switch is closed.

When auxiliary switch 31 is moved into closed position, an energizing circuit will be closed through the heater 6| as follows: From conductor I5 through conductor 85, through engaged contact members 33 and 3|, through conductor 9|, through engaged contact arms 39 and 4|, through conductors 89 and 93, through engaged contact arms 1| and 13, through conductor 95 to the heater 6| and from there through the conf ductor 91 to the other supply circuit conductor I1. This, therefore, provides another heaterenergizing circuit including the auxiliary timercontrolled switch 31 but excluding the auxiliary thermal switch 15 whereby the heater-energizing circuit is made independent of the operative condition of the auxiliary thermal switch 15, energization of the heater 6| under these conditions being therefore dependent more particularly upon whether or not all of the water in the tank is hot, If all of the water in the tank were hot at the time of closure of the auxiliary timer-controlled switch 31, contact arm 13 of the main thermal switch would be out of engagement with its cooperating contact arm 1| and it would, therefore, be impossible to establish energization of the heater 6| and, it is to be further here pointed out, that it would not be desired to continue the energization of the heater 6| since all of the Water in the tank is already hot.`

Referring now to Fig. 2 of the drawings, I have there shown the position of the auxiliary cam disc 41 as moved to one extreme of its adjustable position where it will be operative to ensure energization of the heater 6| at the start of an ofi-peak period irrespective of the condition as to' the amount of hot water in the tank and therefore as to whetherthe auxiliary thermal switch 1 15 is responsive to hot or to cold water. It is evident that the user could be considered to have adjusted the auxiliary cam disc 41 to the position shown in Fig. 2 of the drawings since he knew that the tank contained a relatively small amount of hot water and desired to be sure that heating of the water would be initiated at the start oi an off-peak period.

Referring now to Fig. 3 of the drawings, I have there illustrated a modified form of continuously operative timer particularly as to its control of a plurality of switches actuated thereby into closed and into open positions.

All parts of the system which are the same as or similar to those shown in Fig. 1 of the drawings have been given like numerals and only those parts which differ from those of Fig. `l will be' more specically described hereinafter.

The shaft 23 of the continuously operative timing means has mounted thereon a cam disc I| the greater part of the periphery of which is of uniform radius but which is provided with a portion |03 of larger outer radius which portion is here shown as covering substantially eight hours of a twenty-four hourday, as was hereinbefore set forth for portion 21 of cam disc 25 in Fig. 1 of the drawings. I provide a main timercontrolled switch 29 as hereinbefore described but an auxiliary timer-controlled switch |05, as shown in Fig. 3 of the drawings, is of slightly different construction. It includes a central pivotally mounted Contact arm |01 which is adapted to be moved into engagement -with a left-hand contact arm |09 and a right-hand contact arm I II by the timer. Contact arm |01 has mounted thereon at its outer end a pin ||3 which may be provided with a roller adapted to move in a cam 'slot which may be provided in the outer face of cam disc IOI. This cam slot is of uniform radius over the great part of its periphery but has a portion I1 thereof of predetermined timelength of greater radius so that the arm |01 may be moved into engagement with one arm, and then moved out of engagement therewith and into engagement with the other cooperating contact arm. In the position shown in Fig. 3 of the drawings, pin II3 is shown as positioned in the portion |I1, of larger radius, and thereby moved out of engagement with contact arm I I and into engagement with contact arm |09. It is to be understood that contact arms |09 and III are biased toward each other so that when arm |01 is moved out of engagement with one arm, for instance arm III, and into engagement with contact arm |09, it will not be disengaged from contact arm III until it has engaged contact arm |09, Means for ensuring that disengagement of the outer contact arm from the inner movable contact arm will be eiected is shown as stop members II9 for arm |I| and |2| for arm |09, which stop pins are to be considered as being mounted on some part of the casing in which th'e continuously operative timer I is secured, or in any other suitable or desired manner effective for the desired purpose. The electric circuit connections between the heater, the thermal and the timer-controlled switches are as follows: Supply circuit conductor l5 is connected through a conductor |23 to contact arm 33 and contact arm 3| is connected to contact arm |01 by a conductor |25. Contact arm |09 is connected by a conductor |21 to contact arm 83, while contact arm 8| is connected by conductor 93 to contact arm 1|. Contact arm 13 is connected by conductor to one terminal of heater 6| while the other terminal is connected through a conductor 91 to the other supply circuit conductor I1. Contact arm III is connected by a conductor |29 to conductor 93 and therefore to contact arms 1l and 8| of the main and the auxiliary lthermal switches.

Let it be assumed that at 10:00 p. rn. the position of the parts of the continuously operative timer are as shown in Fig. 3 of the drawings at which time contact arms 33 and 3| of the main timer switch 29 are in engagement as are also contact-arms |01 and |09 of the auxiliary timercontrolled switch |05. If it be assumed that only a relatively small quantity of hot water is in the tank at that time with the result that the auxiliary thermal switch 15 is responsive to cold water, contact arms 83 and 8| will be in engagement with each other and an energizing circuit through the heater will be established as follows: From conductor i5 through conductor |23, through engaged contact arms 33 and 3 I, through conductor |25, through engaged contact arms |01 and |09, through conductor |21, through engaged contact arms 83 and 8|, through conductor 93, through engaged contact arms 1| and 13, from there through conductor 95 to the heater 6| and from there through conductor 91 to the other supply circuit conductor |1.- This means that energization of the heater 6| will be eiiected at the start of an oit-peak period which, of course, is desirous since it is desired to be sure that all of the Water in the tank will be heated before the end of that oit-peak period.

Let it be assumed, on the contrary, that auxiliary switch 15 was subjected to the temperature of hot water but thatless than all of the water in the tank is hot so that the main thermal switch 65 would still be in closed position. The abovedescribed heater-energizing circuit including the main and the auxiliary timer-controlled switches and the auxiliary and the main thermal tank water temperature-responsive switches would not be established since the auxiliary thermal switch 15 would be in open position.

Let it be assumed that the last-named condition obtained at the start oan off-peak period and it is desired to have my improved water heating system effect energization of the heater 6I after a predetermined length of delay time, after the start of an oit-peak period. This will occur when the pin or roller ||3 is moved out of the portion ||1 of the cam slot in the disc |0I as is shown more particularly in Fig. 4 of the drawings, whereby contact arm |01 is moved out of engagement with contact arm |09 and into encagement with contact arm II I whereby another ater-energizing circuit is closed as follows: From supply circuit conductor I through conductor |23, through engaged contact arms 33 and 3|, through conductor |25, through engaged iontact arms I0`I and III, through conductor H29, through engaged contact arms `II and 13, through conductor 95 to heater 6I, and from there through conductor 97 to the other supply circuit conductor I7. It will be noted that this circuit includes the main and the auxiliary timer-controlled switch and the main thermal heater control switch so that energization of the heater is no longer dependent upon what percentage, less than all, of the water content of the tank is hot. It is further evident that as soon as all of the water in the tank is hot, main thermal switch 65 will interrupt the heaterenergizing circuit.

It may be pointed out that should the heater.

be deenergized through its second control circuit as set forth in connection with the systems shown in Figs. l and 3 of the drawings, a substantial time before the end of an off-peak period, and should withdrawals of hot water occur before the end of an OIT-peak period, the heater wouldv again be energized through the last described circuit for the heater and energization would continue until either the end of an ofi-peak period or until all of the water in the tank is hot, deenergization of the heater being effected by either the time-controlled switch or the thermal switch in accordance with which condition is rst to be met with by the system. That is, if all of the water in the tank is not hot by the end of an off-peak period, the time control switching means will effect deenergization of the heater circuit and if substantially all of the water in the tank is hot before the end of an off-peak period, the thermal switch will effect deenergization of the heater.

Various other modications may be made in the systems embodying my invention, without departing from the spirit and scope thereof, and I therefore desire that all such modifications coming clearly within the scope of the appended claims shall be considered to be covered thereby.

I claim as my invention:

1l An off-peak water heating system for a hot water tank having a single electric heater at the lower end of the tank, comprising a main and an auxiliary thermal switch located on the tank at different heights thereon, a main and an auxiliary time-controlled switch adapted to be moved into closed position in predetermined sequenceY manually adjustable means for presetting the time interval between said sequential closing of said time controlled switches, and velectric: connections between all of said switches and the heater, to cause energization of the heater through a circuit including both of said thermal switches and said main time-controlled switch at the start of an o-peak period when less than a predetermined fractional part of the water content of the tank is hot, and to cause energization of the heater through a circuit including both of the time-controlled switches and the main thermal switch after said preset time interval in case less than substantially all of the water in the tank is hot at the end of the delay period.

iliary time-controlled switch adapted to be moved mechanically into closed position in predetermined sequence and with a preset delay period therebetween and electric connections between all of said switches and the heater, energization of the heater being eiected through a circuit including both of said thermal switches in series circuit with each other and said main time-controlled switch only at the start of an off-peak period when less than a predetermined fractional part of the water content of the tank is hot, energization of the heater being precluded for a preset delay period by said auxiliary thermal switch in case more than a predetermined fractional part of the water content of the tank is hot and being then effected through a circuit including both of said time-controlled switches and said main thermal switch and deenergization of the heater being effected by the main timecontrolled switch at the end of an off-peak period in case less than substantially all of the water in the tank is hot at that time.

3. An off-peak water heating system for a hot water tank having a single electric heater near the lower end of the tank, comprising a main and an auxiliary thermal switch located on the tank at different points thereon, a main and an auxiliary time-controlled switch adapted to be moved into closed position in predetermined sequence and electric connections between all of said switches and the heater, energization of the heater being effected through a circuit including both of said thermal switches in series circuit with each other and said main ltime-controlled switch only at the start of an oil-peak period when less than a predetermined fractional part of the water content of the tank is hot, energization of the heater being precluded for a preset delay period by said' auxiliary thermal switch in case more than a predetermined fractional part of the water content of the tank is hot and being then effected through a circuit including both of said time-controlled switches f and said main thermal switch in series circuit 2. An ofi-peak water heating system for a hot' water tank having a single electric heater at the lower end of the tank, comprising a main and an auxiliary thermal switch located on the tank at dierent points thereon, a main and an auxwith each other and deenergization of the heater being effected by the main time-controlled switch at the end of an off-peak period in case less than substantially all of the water in the tank is hot at that time and by the main thermal switch in case substantially all of the water in the tank is hot before the end of the off-peak period.

4. An off-peak Water heating system for a hot water tank having a single electric heater near the bottom of the tank, comprising a continuously operative timer, a main heater control switch adapted to be moved into closed position by said timer at the start of an ofi-peak period, an auxiliary heater control switch adapted to be moved into closed position by said timer at an adjustably preset later time after the start of an ofipeak period, a main thermal heater control switch responsive to tank water temperature and adapted to be moved into open position when substantially all of the water in the tank is hot, an auxiliary thermal heater control switch responsive to tank water temperature and adapted to be moved into open position when a predetermined fractional part of the water content of the tank is hot and electric connections between all of said switches and said heater to cause energization of the heater on closure of said main heater control `switch by the timer through said main switch and said main and auxiliary thermal switches, all in series electric circuit with each other, in case less than said pred-etermined fractional part of the water content of the tank is hot at that time, to preclude energization in case more than said predetermined fractional part of the water content of the tank is hot at that time, to cause energization o! the heater when. .the auxiliary timer-controlled switch is closed and less than substantially all of the water in the tank is hot, said energization continuing until selectively terminated by the main thermal switch in case substantially all of the water in the tank is hot before the end oi an off-peak period and by the main timer-controlled switch at the end of an ofi-peak period in case less than all of the water in the tank is hot at the end of an oiT-peak period.

5. An off-peak water heating system for a hot water tank having ,a single electric heater near the lower end of the tank, comprising a main and an auxiliary thermal heater control switch responsive to tank water temperature at different heights o! the tank, a continuously operative timer, a main heater control switch adapted to be moved into closed position'at the start of an off-peak period, an auxiliary heater control switch adapted to be closed by said timer at an adjustably preset time after the start of an offpeak period and electric connectors connecting said auxiliary timer-controlled switch in shunt circuit relation to said auxiliary thermal switch and interconnecting said other switches to cause energization of the heater at the start of an offpeak period in case less than a predetermined fractional part of the water content ot the tank is hot at the start of an ofi-peak period, to delay energization of the heater until said auxiliary timer-controlled switch is closed in case more than said predetermined fractional part o! the water content of the tank is hot at the start of an oi-peak period, said energization continuing until interrupted selectively by the main timercontrolled switch at the end of an oil-peak period in `case less than substantially all of the water in the\tank is hot at that time or by the main thermal switch before the end of an oi-peak period when all of the water in the tank is hot.

6. An off-peak water heating system for a hot water tank having a single electric heater adjacent to the lower end of the tank, comprising a main and an auxiliary heater control switch, a timer, means driven by the timer for mechanically closing said heater control switches in predetermined sequence with an appreciable time delay therebetween, a lower and an upper thermal heater control switch at diierent heights of the tank and electric connections between all of said switches and said heater to selectively cause energization of said heater through said main timer driven switch and both of said thermal switches at the start of an off-peak period in case less than a predetermined fractional part of the water content of the tank is hot at that time, to preclude energization of the heater at the start of an ofi-peak period if more than said predetermined fractional part of the water content of the tank is hot and to effect energization of the heater through said main and auxiliary timercontrolled switches and said lower thermal switch after a preset iixed delay period.

CLARK M. OSTERHELD. 

